Edwaed weston



(No Model.)

E. WESTON.

SAFETY DEVICE POE ELECTRIC CIRCUITS. No. 259,616. Patented June 13, 1882.

W a /1 WWM 0. 6

UNITED STATES PATENT OFFICE.

EDWARD l-VESTON, OF NEWARK, NEW JERSEY, ASSIGNOR TO THE UNITED STATES ELECTRIC LIGHTING COMPANY, OF NEW YORK, N. Y.

SAFETY DEVICE FOR ELECTRIOCIRCUITS.

SPECIFICATION forming part of Letters Patent No. 259,616, dated June 13, 1882.

Application filed January 5, 1882. (No model.)

To all whom it may concern:

Be it known that I, EDWARD WESTON, a subject of the Queen of Great Britain, and a resident of Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Safety Devices for Electric Circuits, of which the following is a specification, reference being bad to the drawings accompanying and forming a part of the same.

' The subject of my present invention is a safety device for use in electric circuits or branches thereof, with a view of preventing any abnormal flow of current therein or any I 5 accident or injury that might result from such flow.

The invention consists broadly in the combination, with an electric circuit, of a short wire strip or other equivalent conducting medium of higher relative resistance than the conductors of the circuit with which it is connected,devices constructed with a normal tendency to interrupt the continuity of the cir cuit, and a fusible substance surrounded by or in close proximity to the resistance-wire and arranged to maintain the interrupting device in contact, but which allows the same to separate when the resistance-wire becomes heated.

In the accompanying drawings, Figure lis a plan view of my improved safety device; Fig. 2, a side elevation of the same, and Fig. 3 a partly-sectional view of a modification.

A is a small slab or base of insulating material-.-light wood, for instance; B B, binding-posts for connection with the ends of the line-wires.

C C are short standards, clamped to base A. To one-as Ca light spring, 0, is attached, which has a normal tendency to assume the 40 position indicated in dotted lines.

To the other standard, C, spring 0 is fixed. This spring should be under greater tension when the apparatus is set, and for this purpose, when freed, should assume the position 5 indicated by dotted lines.

D is a rest or standard of any description. E is a stick of paraffine, shellac, or some other easily fusible substance, and of such length that it may be held in position between the rest D and a suitable socket or spring, a.

F is a fine platinum, copper, or other wire, which will readily permit the passage of a normal current, but which becomes heated by any marked increase in its flow. It is coiled about the paraffine rod, as shown, and connects the binding-post B with standard 0.

A connecting-wire, G, is used to complete the circuit from standard C to post B.

The operation is as follows: The stick of fusible substance inclosed in the coil F is set in position between spring 0 and standard D. Spring 0 is brought up over the end of spring 0, by which it is retained under tension. In this condition the apparatus permits the flow of current necessary to the requirements of 6 the circuit in which it is included. Should the current increase for any reason beyond the normal limits the coil F becomes heated and softens the stick of fusible material, which, being under compression, bends sufficiently to allow 0 the spring 0 to slip 0% from the end of spring 0 with a snap,the rapidity with which the contact is broken preventing the formation of any injurious sparks.

In order that the material composing the 7 5 stick E may be rendered more sensitive to the action of heat Imakeitof wax,shellac,orsimilar substance, and a small quantity of powdered metal, preferably copper, the two being thoroughly mixed. By this means its heatconducting properties are increased.

It is evident that the above is one only of a great number of ways in which the invention may be carried into effect. For this reason Fig. 3 is giveninillustration of aslightly-niodilied plan. Here, the other parts remaining the same, a slightly-conical plug or button of highly-fusible material, H, in a copper shell, K, of corresponding shape, is substituted for therodorstickE. ThewireFiscarriedaround the shell K, though insulated from it, so that the heat generated by an abnormal flow of current is imparted to the shell. By this means the surface of the fusible plug is softened and the plug itself driven through the shell by 5 springs c and c.

The sticks or plugs of fusible material are easily replaced in the event of their being melted, so that the above forms avery desirable device, not only from the slight expense 10o which its construction involves, but from the absolute safety from accident or injury which its use insures.

Having now described my invention and the best manner of which I am at present aware in which the same is or may be carried into effect, what I claim is- 1, The combination, with an electric circuit, ofawire or similarconducting medium of higher relative resistance than the conductors with which it is connected, a circuit-interrupter, and a mass of fusible material surrounded by or in proximity to the wire of high resistance, and arranged to maintain the continuity of the circuit through the interrupter until softened by heat.

2. In a safety device for electric circuits, the combination, with a circuit-interrupter, of a mass of highly-fusible material for preventing the same from acting, and a resistancewire 20 included in the circuit with the interrupter and in proximity to the fusible material, substantially as set forth.

3. In a safety device for electric circuits, the combination of springs c c, a mass of fusible 25 material for maintaining the same in contact, and a resistance-wire surrounding the fusible material, for the purpose set forth.

at. The rod E, or its equivalent, composed of 1 a non-conducting substance, which softens at 0 a low temperature, and powdered metal for rendering the same a better conductor of heat.

EDWARD WESTON. Witnesses:

W. ScoTT SIMs, J. P. DENGLER. 

